When the Internet was new to consumers, everyone loved email. One of the best parts of logging onto AOL was the knowledge that after minutes of agonizing squeals, you'd be treated to that wonderful phrase, "You've Got Mail!"

But after a couple decades of Nigerian prince schemes, Spanish lotto scams, and mountains of unsolicited spam (which is never a good marketing tactic), how do people feel about email now? Is it still a worthwhile tactic for small-business owners and marketers to pursue?

The simple answer is yes. But you came here to learn, so here are the Top 5 research-backed reasons email marketing is vital for businesses of all sizes:

1. Email is an easy way to reach mobile customers. One reason email marketing has value for business owners is that it's an easy way to start reaching consumers on mobile without investing a lot in new technology or software. According to an April report from Pew Research Center, 52 percent of US cellphone owners access their emails from their phones. Email marketing also works with other mobile devices. In July, Forrester Research released a study that found 42 percent of retailers' email messages were opened by consumers on their smartphones and 17 percent were opened on tablets. This means that nearly three out of every five email marketing messages doubles as a mobile marketing message. Using email is better for mobile marketing than SMS because:

It works on mobile devices other than phones

Emails are free for the consumer, whereas texting may incur a charge

Emails have far more space for content than text messages, allowing for better marketing pieces.

2. It's an effective way to keep customers informed.Email marketing isn't something marketers do just because they can and it's easy. The tactic is very effective at helping business owners and consumers stay connected. In fact, consumers often seek out email marketing campaigns from their favorite brands and local stores. This goes beyond coupons (which we'll discuss next). Nielsen reported that 28 percent of US online shoppers subscribe to store or product emails in order to stay informed. A study from Loyalty 360 stated that 59 percent of US moms would sign up for email updates from brands if rewards were offered. And email marketing can be used as a way to deliver content to consumers. A 2013 study by the Relevancy Group noted that marketers who add video to their email campaigns see an average rise in revenue of 40 percent. There is a real value to staying connected to customers and email marketing makes that easy to do.

3. Email coupons drive online and in-store sales.The Nielsen study mentioned above also found that 27 percent of US online shoppers subscribe to store or product emails in order to save money. This conclusion is backed up by recent data from Deloitte that found 65 percent of consumers say email coupons are important when grocery shopping online. Similarly, Shop.org reported 64 percent of US Internet users have printed a coupon from an email. Though consumers are looking to save money, it can turn into increased revenue for the retailer. E-coupons are big business, and email marketing is at its heart. The number of mobile coupons used is estimated to double over the next five years to reach 1 billion people. Email marketing is a good way to start reaching the growing number of online bargain hunters. The big brands are already using this tactic for that purpose. BIA/Kelsey reports that 36.6 percent of national businesses use email marketing for local promotions.

4. It's easy to customize and integrate into other marketing tactics.The versatility of email marketing is another reason marketers should keep the tactic in their marketing toolbox. Depending on the depth of the email database and the skill of the crafter, email marketing messages can range from simple to very complex. Emails can be personalized to include the name of the user and even more. A small study of 139 marketers from Retention Science found that websites use several kinds of personalization tactics that can easily be applied to email. Nearly half of US online retailers used personalized product recommendations (44.9%), about a third added the customer's name and/or a unique welcome message (31.5%), and a quarter of the respondents reported adding shopping cart reminders (27.6%) to cover all of their personalization bases. Email marketing can also be utilized with just about any other marketing tactic, which makes email an important part of any integrated marketing campaign.

5. Email marketing is inexpensive. To sum up the best reason to use email marketing: It's easy, effective, and inexpensive. Email marketing allows business owners to reach a large number of consumers at a rate of pennies per message. For small-business owners on a budget, this makes it a better choice than traditional marketing channels like TV, radio, or direct mail. You don't have to take my word for it. A joint study from Shop.org and Forrester Research found that 85 percent of US retailers consider email marketing one of the most effective customer acquisition tactics.

The point of all this is that email may be an old tactic, but it remains a vital one. It's relatively easy to get started with email marketing, so there's no excuse for business owners to not be taking advantage of the tactic. Understandably, business owners may be too busy to handle the email marketing on their own, but this is something that any Web marketing professional (wink, wink) can help with. For more information on email marketing, read 10 more stats that show email marketing is still worthwhile and 5 stats that will make you a better email marketer.